Recently, VOC is recognized as one causative agent for so-called sick house syndrome, which causes pollution related health damage such as headaches and dizziness. It is found that this VOC is emitted from electronic apparatuses such as personal computers, copier, printers and the like. For image forming apparatuses among the electronic apparatuses such as copiers and printers, the peculiar odor which generates from heated paper and toner is also a problem, together with the VOC.
In Patent Document 1 (Japanese Unexamined Patent Publication, Tokukai, No. 2005-55515 (Published on Mar. 3, 2005)), a proposal in technology is made towards the problem of the generation of chemical emission such as the VOC or odor as follows: a negative ion generator is provided around the paper output opening provided on the outside of a housing of the image forming apparatus, and the harmful chemical emission being discharged with the paper is decomposed and made harmless by a negative ion. Additionally, the Patent Document 1 discloses a technology providing an odor sensor outside the housing of the image forming apparatus together with the negative ion generator, in which the ON and OFF of the negative ion generator is controlled in accordance with a detection signal from the odor sensor.
However, there are a few problems with the conventional art as described below.
One is that the distance which the negative ion in air can reach from an ion source is limited, for example if there is no wind then the negative ion can only reach up to 100 mm. If the ion generator is provided outside the image forming apparatus (around the transfer paper output opening), the negative ion can only react to the chemical emission discharged and diffused outside the apparatus. The possibility the negative ion would reach the chemical emission is low due to short distance reach of the negative ion, which makes it difficult to effectively reduce the amount of the chemical emission.
Another is that if the negative ion generator is provided outside the housing of the image forming apparatus, the negative ion reacts with nitrogen oxide (NOx) contained in air around the image forming apparatus, causing nitrogen oxide to precipitate outside the housing. This may cause the dirtying of a paper output tray or the housing of the image forming apparatus, or even the wall, floor or the like of the room the image forming apparatus is placed, due to the precipitated nitrogen oxide adhering therewith.
There is also a theory that the negative ion only neutralizes the electric charge of the chemical emission which causes the substance to precipitate, and does not completely decompose and convert the substance to a harmless agent. If the ion generator is provided outside the housing of the image forming apparatus as in Patent Document 1, the once-precipitated VOC may again volatilize (secondary generation), and cause harm.